1. Field of the Invention
The present invention relates to commodity trailers, and more particularly to powered devices for operating commodity trailer hopper trap doors.
2. Description of Related Art
Agricultural and farming industries rely heavily on trucks and commodity trailers to transport products to central distribution centers where the products are accumulated for processing or further shipment. For example, in the case of transporting grain, commodity hopper trailers are often used to carry grain from a farm to a grain elevator, where the grain is stored pending shipment to a buyer.
A typical modern commodity hopper trailer includes at least two separate hopper compartments for carrying the commodity, such as grain, each hopper compartment having an open top for loading the commodity and each hopper compartment having a discharge opening at the bottom for unloading the commodity, with a trap door covering the discharge opening. The trap door covering the discharge opening is often a horizontal sliding panel with an operating linkage adapted to be coupled to a drive shaft, although any other type of operable door covering the discharge opening, such as a hinged drop-door, is also considered a trap door. Typically, the operating linkage is a flat gear along one or both edges of the trap door operably engaged by a circular gear. The drive shaft is typically adjacent the trap door and coupled to the circular gear of the operating linkage via a universal joint, so that rotating the drive shaft turns the universal joint and the circular gear mechanism, which in turn moves the trap door to open or close the discharge opening of the hopper compartment. The drive shaft extends from the underside of the commodity trailer to an outside edge of the trailer, where its top end is accessible. The top end of the driveshaft is adapted to receive a crank handle so that an operator can attach a crank handle to the driveshaft, turn the handle to rotate the driveshaft and the universal joint coupled to the end of the drive shaft, thus moving the operating linkage coupled to the universal joint to open or close the hopper trap door.
In typical use with grain, for example, an operator drives a commodity trailer into position on the unloading ramp of a grain elevator, attaches a crank handle to the upper end of the driveshaft coupled to the operating linkage of the first hopper trap door, and then manually turns the crank handle so that the hopper trap door slides open. As the trap door opens, grain falls from the hopper through the discharge opening, down through the grates of the unloading ramp, and into the grain elevator's unloading ramp storage bins located under the ramp. After the first hopper of the commodity trailer is emptied of grain, the operator closes the hopper trap door by manually cranking the crank handle to rotate the driveshaft in the opposite direction. This unloading operation is then repeated for the second and any additional hopper trap doors, with some smaller unloading ramps requiring the trailer to be moved between unloading each hopper in order to align the hopper trap door with the unloading ramp storage bins.
As can be seen, the process of unloading the hoppers is tedious and labor intensive as each hopper trap door must be manually cranked open and closed. In addition, the time involved in manually operating each trap door is significant, which is particularly undesirable in the situation of a crowded grain elevator where many others are waiting to also unload their grain. Other disadvantages should be apparent to those skilled in the art.